soldering hot water heater connections (newbie)

Hi I have a 1983 condo in Long Beach Ca. I am wanting to replace the hot water heater gate valve (soldered) and the water heater hose that goes to the unit from the water heater. (Also soldered)

My issue is I'm a newbie practiced a few times and of course had no problems.
I'm using propane and the closet is outside in a common hallway.

I have a 3" 1/2" copper piece that is tee'd from a 3/4 or 1' copper line to a 3/4" gate valve that is soldered on both sides then a return 3/4" copper hose to a reducer 1/2" to my condo.

I put a wet rag on the elbow 3" from the return fitting (soldered) and double aluminum to protect the wall waited about 1 min 30" and saw smoke but the old fitting and solder wouldn't budge. I started to worry so stopped. In hindsight I think I lowered the torch a bit due to the small closet space 24x24" I have to turn the water off to 24 units which also stresses me out.

I'm wondering if the extreme temp. outside about 48 (this is Los Angeles!) and the wet rag and my stupidity of not turning the flame up created my problem. I also bought some mapp gas but I was a bit stressed as I mentioned.

The gate valve was probably damaged on the installation since it's not working at all so I do need to turn the water off to the entire building. Any help is appreciated, I'm ticked off that I failed on this and I can obviously hire a plumber but now I'm sort of mad.... My big question is, did the wet rag cause a lot of my problem or was it the flame, On the other side I also have 3" before the tee so I was hoping the wet rag would help me.... Hope this makes sense.

Was there water in the pipe?

3" is more than enough distance away. Rag is okay. I use a rag sometimes when an adjacent fitting is 1" or less away from what I am trying to remove.

Can't really picture what you have with your description. Picture Time!!

Water is your biggest enemy when trying to solder. R U trying to take off the gate valve? Replace it with a good BALL VALVE. Gate valves suck. Stems break and the rarely hold 100%.

I would cut the pipe first using a close-quarters pipe cutter, hacksaw, or sawzall. Upon verifying that absolutely no water remain in the lines then I would use the torch for soldering. Using a torch to try to pull apart a soldered joint can be tricky sometimes. And my preference would be to use a ball valve, gate valves lose it ability to completely shut off over time.

Oh and did you unscrew the nut which connects the water heater to the flex-pipe? If not try doing that first to drain out any water between the water heater and the gate valve.